COOPERATION OF AML1-ETO AND ONCOGENIC KIT IN ACUTE MYELOGENOUS LEUKEMIA

poster abstractA significant portion of AML patients have the cytogenetic abnormality t(8;21) which generates the fusion protein AML1-ETO, leading to a disruption of the core binding factor complex that regulates transcription of hematological genes. Patients harboring the translocation alone usually have a good prognosis; however, a substantial portion of patients bearing an additional oncogenic receptor tyrosine kinase, KIT, mutation have significantly worse prognosis. A mutation of aspartic acid to valine (KITD814V) in the activation loop results in altered substrate recognition and utilization, constitutive tyrosine autophosphorylation, and promiscuous signaling. Little is known concerning possible mechanisms of cooperation between AML1-ETO and KITD814V. Using an IL3 dependent murine myeloid cell line, we show that growth of AML1-ETO bearing cells remain ligand dependent, while cells that express both AML1-ETO and KITD814V demonstrate ligand independent proliferation. Furthermore, functional assays show that expression of AML1-ETO and KITD814V leads to an increase in cell cycling and decrease in apoptosis that may contribute to the observed ligand independent proliferation. Using a syngenic murine transplantation model we demonstrate that mice transplanted with AML1-ETO and KITD814V bearing cells succumb to a fatal myeloproliferative disease (MPD)-like phenotype, while AML1-ETO expressing mice remain disease free. This suggests that AML1-ETO alone is not sufficient to induce ligand independent growth, nor MPD, but may cooperate with KITD814V to enhance proliferation. Continuing research aims to investigate mechanisms of cooperation between KITD814V and AML1-ETO that contribute to ligand independent growth in vitro, transformation in vivo, and poor overall prognosis in AML patients bearing the two mutations

CYP72A enzymes catalyse 13-hydrolyzation of gibberellins

Bioactive gibberellins (GAs, diterpenes) are essential hormones in land plants, controlling many aspects of plant growth and developments. In flowering plants, 13-OH (low bioactivity; such as GA1) and 13-H GAs (high bioactivity; such as GA4) frequently coexist. However, the bona fide GA 13-hydroxylase and its physiological functions in Arabidopsis remain unknown. Here, we report that novel cytochrome P450 genes (CYP72A9 and its homologs) encode active GA 13- hydroxylases in Brassicaceae plants. CYP72A9-overexpressing plants exhibited semi-dwarfism, which was caused by significant reduction in GA4 levels. Biochemical assays revealed that recombinant CYP72A9 protein catalyzed the conversion from 13-H GAs to the corresponding 13-OH GAs. CYP72A9 was expressed predominantly in developing seeds in Arabidopsis. Freshly harvested seeds of cyp72a9 mutants germinated more quickly than wild-type, while long-term storage and stratification-treated seeds did not. The evolutionary origin of GA 13- oxidases from the CYP72A subfamily also was investigated and discussed here

Role of intracellular tyrosines in activating KIT induced myeloproliferative disease

Gain-of-function mutations in KIT receptor in humans are associated with gastrointestinal stromal tumors (GIST), systemic mastocytosis (SM), and acute myelogenous leukemia (AML). The intracellular signals that contribute to oncogenic KIT induced myeloproliferative disease (MPD) are poorly understood. Here, we show that oncogenic KITD814V induced MPD occurs in the absence of ligand stimulation. The intracellular tyrosine residues are important for KITD814V induced MPD, albeit to varying degrees. Among the seven intracellular tyrosines examined, tyrosine 719 alone plays a unique role in regulating KITD814V induced proliferation and survival in vitro, and MPD in vivo. Importantly, the extent to which AKT, ERK and Stat5 signaling pathways are activated via the seven intracellular tyrosines in KITD814V impacts the latency of MPD and severity of the disease. Our results identify critical signaling molecules involved in regulating KITD814V induced MPD, which might be useful for developing novel therapeutic targets for hematologic malignancies involving this mutation

S6K1 regulates hematopoietic stem cell self-renewal and leukemia maintenance.

Hyperactivation of the mTOR pathway impairs hematopoietic stem cell (HSC) functions and promotes leukemogenesis. mTORC1 and mTORC2 differentially control normal and leukemic stem cell functions. mTORC1 regulates p70 ribosomal protein S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E–binding (eIF4E-binding) protein 1 (4E-BP1), and mTORC2 modulates AKT activation. Given the extensive crosstalk that occurs between mTORC1 and mTORC2 signaling pathways, we assessed the role of the mTORC1 substrate S6K1 in the regulation of both normal HSC functions and in leukemogenesis driven by the mixed lineage leukemia (MLL) fusion oncogene MLL-AF9. We demonstrated that S6K1 deficiency impairs self-renewal of murine HSCs by reducing p21 expression. Loss of S6K1 also improved survival in mice transplanted with MLL-AF9–positive leukemic stem cells by modulating AKT an

Role of p85α in neutrophil extra- and intracellular reactive oxygen species generation

Drug resistance is a growing problem that necessitates new strategies to combat pathogens. Neutrophil phagocytosis and production of intracellular ROS, in particular, has been shown to cooperate with antibiotics in the killing of microbes. This study tested the hypothesis that p85α, the regulatory subunit of PI3K, regulates production of intracellular ROS. Genetic knockout of p85α in mice caused decreased expression of catalytic subunits p110α, p110β, and p110δ, but did not change expression levels of the NADPH oxidase complex subunits p67phox, p47phox, and p40phox. When p85α, p55α, and p50α (all encoded by Pik3r1) were deleted, there was an increase in intracellular ROS with no change in phagocytosis in response to both Fcγ receptor and complement receptor stimulation. Furthermore, the increased intracellular ROS correlated with significantly improved neutrophil killing of both methicillin-susceptible and methicillin-resistant S. aureus. Our findings suggest inhibition of p85α as novel approach to improving the clearance of resistant pathogens

Large-scale on-chip integration of gate-voltage addressable hybrid superconductor-semiconductor quantum wells field effect nano-switch arrays

Stable, reproducible, scalable, addressable, and controllable hybrid superconductor-semiconductor (S-Sm) junctions and switches are key circuit elements and building blocks of gate-based quantum processors. The electrostatic field effect produced by the split gate voltages facilitates the realisation of nano-switches that can control the conductance or current in the hybrid S-Sm circuits based on 2D semiconducting electron systems. Here, we experimentally demonstrate a novel realisation of large-scale scalable, and gate voltage controllable hybrid field effect quantum chips. Each chip contains arrays of split gate field effect hybrid junctions, that work as conductance switches, and are made from In0.75Ga0.25As quantum wells integrated with Nb superconducting electronic circuits. Each hybrid junction in the chip can be controlled and addressed through its corresponding source-drain and two global split gate contact pads that allow switching between their (super)conducting and insulating states. We fabricate a total of 18 quantum chips with 144 field effect hybrid Nb- In0.75Ga0.25As 2DEG-Nb quantum wires and investigate the electrical response, switching voltage (on/off) statistics, quantum yield, and reproducibility of several devices at cryogenic temperatures. The proposed integrated quantum device architecture allows control of individual junctions in a large array on a chip useful for the development of emerging cryogenic nanoelectronics circuits and systems for their potential applications in fault-tolerant quantum technologies

Simultaneous bilateral hip replacement reveals superior outcome and fewer complications than two-stage procedures: a prospective study including 1819 patients and 5801 follow-ups from a total joint replacement registry

<p>Abstract</p> <p>Background</p> <p>Total joint replacements represent a considerable part of day-to-day orthopaedic routine and a substantial proportion of patients undergoing unilateral total hip arthroplasty require a contralateral treatment after the first operation. This report compares complications and functional outcome of simultaneous versus early and delayed two-stage bilateral THA over a five-year follow-up period.</p> <p>Methods</p> <p>The study is a post hoc analysis of prospectively collected data in the framework of the European IDES hip registry. The database query resulted in 1819 patients with 5801 follow-ups treated with bilateral THA between 1965 and 2002. According to the timing of the two operations the sample was divided into three groups: I) 247 patients with simultaneous bilateral THA, II) 737 patients with two-stage bilateral THA within six months, III) 835 patients with two-stage bilateral THA between six months and five years.</p> <p>Results</p> <p>Whereas postoperative hip pain and flexion did not differ between the groups, the best walking capacity was observed in group I and the worst in group III. The rate of intraoperative complications in the first group was comparable to that of the second. The frequency of postoperative local and systemic complication in group I was the lowest of the three groups. The highest rate of complications was observed in group III.</p> <p>Conclusions</p> <p>From the point of view of possible intra- and postoperative complications, one-stage bilateral THA is equally safe or safer than two-stage interventions. Additionally, from an outcome perspective the one-stage procedure can be considered to be advantageous.</p

Expansion within the CYP71D subfamily drives the heterocyclization of tanshinones synthesis in Salvia miltiorrhiza

Tanshinones are the bioactive nor-diterpenoid constituents of the Chinese medicinal herb Danshen (Salvia miltiorrhiza). These groups of chemicals have the characteristic furan D-ring, which differentiates them from the phenolic abietane-type diterpenoids frequently found in the Lamiaceae family. However, how the 14,16-epoxy is formed has not been elucidated. Here, we report an improved genome assembly of Danshen using a highly homozygous genotype. We identify a cytochrome P450 (CYP71D) tandem gene array through gene expansion analysis. We show that CYP71D373 and CYP71D375 catalyze hydroxylation at carbon-16 (C16) and 14,16-ether (hetero)cyclization to form the D-ring, whereas CYP71D411 catalyzes upstream hydroxylation at C20. In addition, we discover a large biosynthetic gene cluster associated with tanshinone production. Collinearity analysis indicates a more specific origin of tanshinones in Salvia genus. It illustrates the evolutionary origin of abietane-type diterpenoids and those with a furan D-ring in Lamiaceae